source: trunk/target/linux/generic/files/drivers/char/gpio_dev.c @ 21952

Last change on this file since 21952 was 21952, checked in by nbd, 6 years ago

rename target/linux/generic-2.6 to generic

File size: 4.0 KB
Line 
1/*
2 * character device wrapper for generic gpio layer
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307USA
17 *
18 * Feedback, Bugs...  blogic@openwrt.org
19 *
20 * dpg 20100106
21 */
22
23#include <linux/module.h>
24#include <linux/errno.h>
25#include <linux/init.h>
26#include <asm/uaccess.h>
27#include <asm/io.h>
28#include <asm/gpio.h>
29#include <asm/atomic.h>
30#include <linux/init.h>
31#include <linux/genhd.h>
32#include <linux/device.h>
33#include <linux/platform_device.h>
34#include <linux/gpio_dev.h>
35
36#define DRVNAME         "gpiodev"
37#define DEVNAME         "gpio"
38
39static int dev_major;
40static struct class *gpiodev_class;
41
42
43/* third argument of user space ioctl ('arg' here) contains the <pin> */
44static int
45gpio_ioctl(struct inode * inode, struct file * file, unsigned int cmd,
46           unsigned long arg)
47{
48        int retval = 0;
49
50        switch (cmd)
51        {
52        case GPIO_GET:
53                retval = gpio_get_value(arg);
54                break;
55        case GPIO_SET:
56                gpio_set_value(arg, 1);
57                break;
58        case GPIO_CLEAR:
59                gpio_set_value(arg, 0);
60                break;
61        case GPIO_DIR_IN:
62                retval = gpio_direction_input(arg);
63                break;
64        case GPIO_DIR_OUT:
65                retval = gpio_direction_output(arg, 0);
66                break;
67        case GPIO_DIR_HIGH:
68                retval = gpio_direction_output(arg, 1);
69                break;
70        case GPIO_REQUEST:
71                /* should be first ioctl operation on <pin> */
72                retval = gpio_request(arg, DRVNAME);
73                break;
74        case GPIO_FREE:
75                /* should be last ioctl operation on <pin> */
76                /* may be needed first if previous user missed this ioctl */
77                gpio_free(arg);
78                break;
79        case GPIO_CAN_SLEEP:
80                retval = gpio_cansleep(arg);
81                break;
82        default:
83                retval = -EINVAL;
84                /* = -ENOTTY; // correct return but ... */
85                break;
86        }
87        return retval;
88}
89
90/* Allow co-incident opens */
91static int
92gpio_open(struct inode *inode, struct file *file)
93{
94        int result = 0;
95        unsigned int dev_minor = MINOR(inode->i_rdev);
96
97        if (dev_minor != 0)
98        {
99                printk(KERN_ERR DRVNAME ": trying to access unknown minor device -> %d\n", dev_minor);
100                result = -ENODEV;
101                goto out;
102        }
103out:
104        return result;
105}
106
107static int
108gpio_close(struct inode * inode, struct file * file)
109{
110        /* could track all <pin>s requested by this fd and gpio_free()
111         * them here
112         */
113        return 0;
114}
115
116struct file_operations gpio_fops = {
117        ioctl:          gpio_ioctl,
118        open:           gpio_open,
119        release:        gpio_close
120};
121
122static int
123gpio_probe(struct platform_device *dev)
124{
125        int result = 0;
126
127        dev_major = register_chrdev(0, DEVNAME, &gpio_fops);
128        if (!dev_major)
129        {
130                printk(KERN_ERR DRVNAME ": Error whilst opening %s \n", DEVNAME);
131                result = -ENODEV;
132                goto out;
133        }
134        gpiodev_class = class_create(THIS_MODULE, DRVNAME);
135        device_create(gpiodev_class, NULL, MKDEV(dev_major, 0), dev, DEVNAME);
136        printk(KERN_INFO DRVNAME ": gpio device registered with major %d\n", dev_major);
137out:
138        return result;
139}
140
141static int
142gpio_remove(struct platform_device *dev)
143{
144        unregister_chrdev(dev_major, DEVNAME);
145        return 0;
146}
147
148static struct
149platform_driver gpio_driver = {
150        .probe = gpio_probe,
151        .remove = gpio_remove,
152        .driver = {
153                .name = "GPIODEV",
154                .owner = THIS_MODULE,
155        },
156};
157
158static int __init
159gpio_mod_init(void)
160{
161        int ret = platform_driver_register(&gpio_driver);
162        if (ret)
163                printk(KERN_INFO DRVNAME ": Error registering platfom driver!\n");
164
165        return ret;
166}
167
168static void __exit
169gpio_mod_exit(void)
170{
171        platform_driver_unregister(&gpio_driver);
172}
173
174module_init (gpio_mod_init);
175module_exit (gpio_mod_exit);
176
177MODULE_LICENSE("GPL");
178MODULE_AUTHOR("John Crispin / OpenWrt +");
179MODULE_DESCRIPTION("Character device for for generic gpio api");
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